Hereditary Diseases of Sheep and Pi(js. 
29 
the blood from without, as in the food, or accumulated there 
from the imperfect action of such orjjans as the skin or kidneys. 
Nature separates these irritant matters from the blood by the 
intestinal mucous membrane with its glandular apparatus, which 
becomes stimulated to increased activity and augmented secretion 
by the local action of the irritant. The complaint is sometimes 
caused by the lodgment in the intestines of acrid, indigestible 
food, which induces a local irritant action, and a consequent 
increase in the movements and secretions of the canal. It is 
also occasionally caused or kept up by an undue amount of fluid 
being poured into the canal from the relaxed intestinal vessels. 
Diarrhoea in healthy stock, and when early attended to, may 
usually be speedily arrested by a change of pasture, dry food, 
and sufficient shelter ; but when it occurs in animals witli weak 
intestines or a vitiated constitution, and especially if it have been 
allowed to go on neglected, it is very apt to be the precursor of 
di/sentcrt/- This last disease sometimes continues for many 
months, sometimes only for a few weeks. The animal first falls 
off in condition ; he appears " to do no good," to use a familiar 
but expressive phrase. His thirst is excessive, his appetite 
irregular and capricious, and his rumination imperfect. The 
wool is dry and hard, and the skin covered with a dingy yellow 
scurf; the faeces are evacuated forcibly, with straining and pain, 
and contain imperfectly-digested portions of the food, witli 
dark-coloured mucus and blood ; the back is arched and the 
belly tucked up ; the pulse is weak, soft, and compressible, and 
seldom above seventy. Respiration is somewhat accelerated, 
and a cough is generally induced by tubercles in the lungs or 
liver. The sheep occasionally kicks at its belly as if suffering 
pain ; serous effusions appear underneath the jaws, at the brisket, 
and in the limbs, and other dependent parts — sure indications of 
impoverished and vitiated blood ; the breath and all the secre- 
tions become foetid, the strength fails, and the animal, worn to a 
skeleton, dies from utter exhaustion. With such decided symp- 
toms as these, indicating in the most striking manner the nature 
of the disease, it is strange that any one would gravely propose 
to treat it by bloodletting ; yet Mr. Youatt and others have 
recommended bleeding and several doses of physic, for the pur- 
pose (say they) of overcoming the inflammation and fever.* 
But the inflammation of dysentery is of a sub-acute and vitiated 
kind, and is hence greatly aggravated by the abstraction of blood ; 
and the fever is of a low typhoid type, requiring tonics and 
stimulants rather than antiphlogistics. We merely advert to 
this error as indicating the essential importance of understanding 
* Youatt on Sheep, p. 470. 
